1. Field of the Invention
The present invention relates generally to the field of communication systems and, more particularly, to data communications over a telephone network.
2. Background Information
Land based telephone systems have been in existence for many years. Existing telephone networks use twisted pair copper telephone wire to connect telephones and other equipment to a centralized Public Switched Telephone Network (PSTN) switch located at a Central Office (CO) or remote CO providing connectivity to other telephones or equipment. Up until recently, the predominant use of the twisted pair wire connecting telephones to the PSTN switch has been for traditional telephony functions such as for example voice conversation using a Plain Old Telephone Service (POTS) telephone call. With the advent of Internet and the World Wide Web, the twisted pair wires in existing telephone networks have begun carrying increasing amounts of digitized data for extended periods of time.
To illustrate, FIG. 1 shows a prior art telephone network 101 including a PSTN switch 105 providing connectivity to a plurality of telephones, such as remote telephones 107 and 109. As can be appreciated to those skilled in the art, PSTN switch 105 may be any one of a plurality of PSTN switches coupled together in a PSTN. Remote telephone 107 is coupled to PSTN switch 105 through twisted pair wire 115. Remote telephone 109 is coupled to PSTN switch 105 through twisted pair wire 117. During typical telephony operation, remote telephone 107 can communicate with remote telephone 109 through twisted pair wire 115, PSTN switch 105 and twisted pair wires 117 or to any other telephone in the PSTN.
As discussed, there is an increasing demand for telephone network 101 to carry digital information over the existing twisted pair wires to allow remote computer systems, such as for example client system 113, to communicate other systems, such as for example Internet Service Providers (ISPs), which may be represented as host system 103 in FIG. 1. Client system 113 is coupled to twisted pair wire 117 through remote modem 111. Host system 103 is typically coupled to PSTN switch 105 through a high speed data interface 119. Accordingly, data communications are provided between host system 103 and client system 113 through PSTN switch 105, twisted pair wire 117 and remote modem 111.
This continuing trend of using existing telephone networks for data communications has created some concern for the operators of the PSTN since virtually all of their switching equipment was initially intended to carry only short duration voice calls. Indeed, many PSTN switches are carrying more communications traffic volume than which they were originally designed.
In view of the foregoing, what is desired is a method and apparatus that permits data communications at high data rates over existing twisted pair wires of existing telephone networks without burdening the PSTN switches. Furthermore, such a method and apparatus should be able to be coupled to existing PSTN twisted pair wires with little or no modification and without interfering with normal telephony functions.